EP0569371B1 - Process for the preparation of powdered tenside mixtures - Google Patents

Abstract

Essentially, the process consists in mixing 15 to 50 parts by weight of alkyl sulphate of the formula R?1-OSO3?X, in which R?1 is an alkyl radical with 10 to 20 C atoms and X is an alkali, ammonium, alkyl or hydroxyalkyl-substituted ammonium, 1 to 5 parts by weight of alkyl glycoside of the formula R?2-O(G)n?, in which R?2 is an alkyl radical with 8 to 22 C atoms, G is a glycose unit and n a number from 1 to 10, whereby the ratio by weight of alkyl sulphate to alkyl glycoside is 25:1 to 8:1, and 45 to 80 parts by weight of an inorganic carrier consisting of at least 7 % wt. alkali silicate with a mol ratio of SIO2? to alkali oxide of over 2, with enough water to obtain a mixture which is fluid and can be pumped at temperatures below 80 C with a viscosity from 3000 mPa.s to 15000 mPa.s measured at 60 to 75 C, and extracting the water therefrom by spray drying or the use of drying gases at temperatures below 250 C until a powdered, fluid product is obtained. The tenside mixtures thus obtainable are preferably used to make particulate washing and cleaning agents.

Description

The invention relates to a process for producing powdery, pourable and free-flowing surfactant mixtures which contain alkyl sulfate, alkyl glycoside and inorganic carrier material.

International patent application WO 90/04630 discloses a process for producing particulate detergents by spray drying an aqueous slurry containing 15 to 50 parts by weight of water and 50 to 85 parts by weight of a non-aqueous composition, the latter 2 to 50 parts by weight .-% anionic and / or nonionic surfactant, 10 to 70 wt .-% alkali carbonate as a builder and in addition to other optional ingredients contains a viscosity-reducing amount of a combination of alkyl glycoside and alkali chloride. Preferred anionic surfactants there are the alkylbenzenesulfonates.

From the international patent application WO 87/02053 a process for the production of particulate detergents by drying a 40 to 80 percent aqueous slurry is known, which, based on the resulting solid, 2 to 60 wt .-% surfactants, which are at least 0.1 wt. % consist of alkyl glycosides, the total amount of alkyl glycosides being at most 2% by weight, containing 5 to 70% by weight of builder substances and up to 40% by weight of water-soluble fillers. In such slurries, the alkyl glycosides act as lower viscosity. Preferred surfactants are anionic surfactants, especially those of the alkylbenzenesulfonate type, and nonionic surfactants, especially ethoxylated fatty alcohols. The removal of water from the slurry is preferably accomplished by spray drying.

The use of alkylbenzenesulfonate in detergents and cleaning agents has recently been called into question because of the petroleum base of this surfactant. For example, sulfation products of compounds accessible from renewable raw materials, in particular fatty alcohols, come into consideration as more environmentally compatible surfactants with comparable good cleaning properties. However, while aqueous slurries containing alkylbenzenesulfonate can be spray-dried without problems at the temperatures customary in such processes, normally about 250 ° C. to 350 ° C., there is a risk of spontaneous combustion in aqueous slurries which contain the same amount of alkyl sulfates.

The object was therefore to develop a process which allows the preparation of powdered surfactant mixtures free of alkylbenzenesulfonate by spray drying an aqueous slurry while avoiding the problems mentioned.

This object is achieved by the process according to the invention for the production of powdered surfactant mixtures by mixing alkyl sulfate, alkyl glycoside and an inorganic carrier material which contains alkali silicate with water and then spray-drying the flowable, aqueous, surfactant-containing mixture, which process is characterized in that 15 up to 50 parts by weight of alkyl sulfate of the formula I,

R¹-OSO₃X (I)

in which R¹ is an alkyl radical having 10 to 20 C atoms and X is an alkali, ammonium or alkyl or hydroxyalkyl-substituted ammonium ion, 1 to 5 parts by weight of alkyl glycoside of the formula II,

RO (G) _n (II)

in which R is an alkyl radical having 8 to 22 carbon atoms, G is a glycose unit and n is a number from 1 to 10, the weight ratio of alkyl sulfate to alkyl glycoside being 25: 1 to 8: 1, and 45 to 80 parts by weight of an inorganic carrier material , which consists of at least 7 wt .-% of alkali silicate with a molar ratio of SiO₂ to alkali oxide over 2, mixed with so much water that a 35 wt .-% to 50 wt .-% water containing, flowable at temperatures below 80 ° C. and pumpable mixture is formed, and this removes the water by spray drying using drying gases at temperatures below 250 ° C. to such an extent that a powdery, free-flowing product is formed.

This is usually the case when the water content in the powder product is not more than 15% by weight, in particular from 5% by weight to 15% by weight. In formulations in which the carrier material binds part of the water as crystal water, the residual water content relates to the free water not bound in the crystal lattice.

The process is preferably carried out in such a way that 20 to 40 parts by weight of alkyl sulfate according to formula I, 2 to 4 parts by weight of alkyl glycoside according to formula II and 48 to 68 parts by weight of the inorganic carrier material are mixed with so much water that a 40% by weight to 50% by weight .-% water-containing mixture is formed.

The inorganic carrier material preferably consists of 20 to 50 wt .-% of alkali silicate with a molar ratio of SiO₂ to alkali oxide over 2, in particular from 2.5 to 3.5. The preferred alkali metal is sodium. In addition to the alkali silicate, other water-soluble and after drying particulate inorganic carrier materials can be used. The alkali carbonates, bicarbonates and sulfates and mixtures thereof are particularly suitable. It is also possible to incorporate water-insoluble carrier materials, which include, in particular, layered silicates, for example bentonites or smectites, and aluminosilicates, for example zeolites.

The spray-drying of the aqueous slurries is carried out in equipment usually provided for this purpose, so-called spray towers, in the upper part of which the slurry is sprayed into fine droplets by pressure nozzles, which move under the action of gravity into the lower part of the spray tower and come into contact with hot drying gases which are guided in cocurrent or preferably in countercurrent to the particles to be dried. It should be ensured that the temperature of the drying gases is not so high that the temperature. of the spray-dried particles rises above the self-ignition temperature of these particles. In the context of the invention, this means that the temperature of the drying gases does not exceed a value of 250 ° C. and is preferably in the range from 120 ° C. to 240 ° C., in particular from 140 ° C. to 210 ° C., the drying gas temperature being the hottest Location of the drying tower, the so-called ring channel, is measured.

In the preparation of the slurries leading to the mixtures prepared according to the invention, it is possible to incorporate aqueous, generally 30 to 60 percent by weight alkyl glycoside pastes, as are usually obtained in the course of the production of alkyl glycosides and, if appropriate, subsequent bleaching. Likewise, the alkyl sulfate component and in particular the carrier component can be used as an aqueous solution or slurry. In order to ensure the easy flow and pumpability of the slurry to be sprayed at temperatures below 80 ° C., it has proven to be advantageous if 40 to 50% by weight of water is present in the slurry to be dried. Here As a further advantage of the process according to the invention, the surprisingly low viscosity of the slurries leading to the compounds according to the invention compared to slurries which instead of alkyl sulfate with values in the range from 3,000 mPas to 15,000 mPas at temperatures from 60 ° C. to 75 ° C. contain the same amount of alkylbenzenesulfonate.

The powdery, pourable and free-flowing surfactant mixtures produced by the process according to the invention contain 15 to 50% by weight of alkyl sulfate of the formula I,

R¹-OSO₃X (I)

in which R¹ is an alkyl radical having 10 to 20 C atoms and X is an alkali, ammonium or alkyl or hydroxyalkyl-substituted ammonium ion, 1 to 5% by weight of alkyl glycoside of the formula II,

RO (G) _n (II)

in which R is an alkyl radical having 8 to 22 carbon atoms, G is a glycose unit and n is a number from 1 to 10, the weight ratio of alkyl sulfate to alkyl glycoside being 25: 1 to 8: 1, and 45 to 80% by weight an inorganic carrier material, which consists of at least 7 wt .-% of alkali silicate with a molar ratio SiO₂ to alkali oxide greater than 2.

Suitable alkyl sulfates for use in the process according to the invention are the compounds of the formula I in which R 1 is an alkyl radical having 10 to 20 carbon atoms and X is an alkali metal, ammonium or alkyl or hydroxyalkyl-substituted ammonium ion. The derivatives of fatty alcohols with in particular 12 to 18 carbon atoms and their branched-chain analogs, the so-called oxo alcohols, are particularly suitable. The alkyl sulfates can be prepared in a known manner by reacting the corresponding alcohol component with a conventional sulfating reagent, in particular sulfur trioxide or chlorosulfonic acid, and then neutralizing with alkali, ammonium or alkyl or hydroxyalkyl-substituted ammonium bases. Such alkyl sulfates are present in the compounds produced according to the invention in amounts of from 15% by weight to Contain 50% by weight, preferably from 20% by weight to 40% by weight.

The alkyl glycosides suitable for incorporation into the compounds prepared according to the invention are compounds of the general formula II in which R is an alkyl radical having 8 to 22 carbon atoms, G is a glycose unit and n is a number between 1 and 10. Such alkyl glycosides and their preparation are described, for example, in European patent applications EP 92 355, EP 301 298, EP 357 969 and EP 362 671 or the US Pat. No. 3,547,828. The glycoside component ((G) _n in formula II) of such alkyl glycosides are oligomers or polymers from naturally occurring aldose or ketose monomers, in particular glucose, mannose, fructose, galactose, talose, gulose, altrose, allose , Idose, ribose, arabinose, xylose and lyxose. The oligomers consisting of such glycosidically linked monomers are characterized not only by the type of sugar they contain, but also by their number, the so-called degree of oligomerization. The degree of oligomerization (n in formula II) generally assumes fractional numerical values as the quantity to be determined analytically; it is between 1 and 10, with the alkyl glycosides preferably used below a value of 1.5, in particular between 1.2 and 1.4. The preferred monomer building block is glucose because of its good availability.

The alkyl part (R in formula II) of the alkyl glycosides preferably also originates from easily accessible derivatives of renewable raw materials, in particular from fatty alcohols, although their branched chain isomers, in particular so-called oxo alcohols, can also be used to prepare alkyl glycosides which can be used. Accordingly, the primary alcohols with linear octyl, decyl, dodecyl, tetradecyl, hexadecyl or octadecyl radicals and mixtures thereof are particularly useful. Particularly suitable alkyl glycosides contain a coconut fatty alkyl radical, that is to say mixtures with essentially R1 = dodecyl and R1 = tetradecyl. The alkyl glycosides can contain small amounts, for example 1 to 2%, of unreacted free fatty alcohol, which does not have a disadvantageous effect on the properties of the compounds produced therewith.

Such alkyl glycosides are contained in the compounds produced according to the invention in amounts of 1% by weight to 5% by weight, preferably 2% by weight to 4% by weight, the weight ratio of alkyl sulfate to alkyl glycoside being 25: 1 to 8 : 1, preferably 20: 1 to 10: 1.

In addition, the mixtures prepared according to the invention can contain further surfactants, preferably nonionic surfactants and / or anionic surfactants, and in particular soils of the sulfate or sulfonate type, in amounts of preferably not more than 10% by weight, in particular from 1% by weight to 5 % By weight. The sulfate-type surfactants which can also be used include the sulfated alkoxylation products of the alcohols mentioned, so-called ether sulfates. Such ether sulfates preferably contain 2 to 30, in particular 4 to 10, ethylene glycol groups per molecule. Suitable anionic surfactants also include the α-sulfoesters obtainable by reacting fatty acid esters with sulfur trioxide and subsequent neutralization, in particular those derived from fatty acids with 8 to 22 C atoms, preferably 12 to 18 C atoms, and linear alcohols with 1 to 6 C -Atoms, preferably 1 to 4 carbon atoms, derived sulfonation products.

The nonionic surfactants in question include the alkoxylates, in particular the ethoxylates and / or propoxylates of linear or branched-chain alcohols having 10 to 22 carbon atoms, preferably 12 to 18 carbon atoms. The degree of alkoxylation of the alcohols is between 1 and 20, preferably between 3 and 10. They can be prepared in a known manner by reacting the corresponding alcohols with the corresponding alkylene oxides. The derivatives of fatty alcohols are particularly suitable, although their branched chain isomers, in particular so-called oxo alcohols, can also be used to prepare alkoxylates which can be used. Accordingly, the ethoxylates of primary alcohols with linear dodecyl, tetradecyl, hexadecyl or octadecyl radicals and mixtures thereof are particularly useful. Corresponding ethoxylation and / or propoxylation products of alkylamines, vicinal diols and carboxamides which correspond to the alcohols mentioned with regard to the alkyl part can also be used.

Carrier substances are contained in the mixtures produced according to the invention in amounts of 45% by weight to 80% by weight, preferably 48% by weight to 68% by weight, it being essential that at least 7% by weight of the carrier material , preferably 20 wt .-% to 45 wt .-%, consist of the alkali silicate mentioned.

In addition, the mixtures produced according to the invention can contain further constituents which are customary in washing and cleaning agents and are stable under the drying conditions. These optional components include in particular complexing agents for heavy metals, for example aminopolycarboxylic acids and / or polyphosphonic acids, graying inhibitors, for example cellulose ethers, cobuilders, for example polymer polycarboxylic acids, foam inhibitors, for example organopolysiloxanes or paraffins, and optical brighteners, for example stilbene disulfonic acid derivatives.

The powdery surfactant mixtures produced according to the invention are used in particular as pourable and free-flowing preliminary products (compounds) for the production of particulate detergents or cleaning agents.

For use as premixes for the production of powdered detergents and cleaning agents, the compounds produced according to the invention should have average grain sizes of preferably 0.2 mm to 0.4 mm and should be largely free of particles with a diameter of more than 2 mm or less than 50 μm. These limits are normally met by the compounds obtained by spray drying, otherwise particles outside this size range can be removed by simple sieving and returned to the manufacturing process. The bulk density of the compounds according to the invention is preferably between 120 and 500 grams per liter and can therefore differ considerably from that of the other powdery constituents of a finished washing or cleaning agent, normally without segregation occurring.

The compounds produced according to the invention are free-flowing powders which do not lose their advantageous properties even after prolonged storage. For the production of cleaning agents or detergents, these compounds can be mixed with other compounds in a manner known in principle Such agents are mixed with conventional powdery constituents, which include, in particular, abrasives, for example quartz powder, bleaching agents, for example perborates or percarbonates, and bleach activators, for example multi-acylated alkylenediamines, carboxylic acid anhydrides or multi-acylated polyols. The spraying of liquid, liquefied or dissolved ingredients, for example enzymes, dyes, fragrances or other surfactants, in particular nonionic surfactants, onto the compounds produced according to the invention is also possible in a manner known in principle.

Examples example 1

By heating the alkyl glycoside component to approx. 60 ° C., adding it to the aqueous alkyl sulfate solution and adding the other components with stirring, the zeolite being used in the form of an approx. 50% by weight aqueous slurry and the sodium silicate being in the form of an approx. 35% by weight water glass solution was added as the last component, aqueous slurries were produced from the raw materials given in Table 1, which contained 40 to 44 wt .-% water. These slurries, which had the viscosities given in Table 2 at 65 ° C, were heated to temperatures of about 60 ° C to 80 ° C and sprayed under a pressure of 40 bar in a drying tower, hot air (temperature 145 ° C to 160 ° C in the ring channel) was conducted in countercurrent. The free-flowing powders characterized in Table 1 by their composition were obtained with average grain sizes around 300 μm, which were free of particles over 1.6 mm in diameter, had dust contents of 0.1 to 0.65% by weight and bulk densities of 145 owned up to 270 grams per liter.

Table 2: Slurry viscosity [mPa˙s] at 65 ° C Slurry for compound Concentration [% by weight] Viscosity [mPa · s] M1 58 4800 M2 60 7000 M3 60 4700 M4 60 5200

Claims (7)

1. A process for the production of powder-form surfactant mixtures by mixing alkyl sulfate, alkyl glycoside and an inorganic carrier material containing alkali metal silicate with water and spray-drying the flowable, aqueous surfactant-containing mixture, characterized in that 15 to 50 parts by weight of alkyl sulfate corresponding to formula I:
   
           R¹-OSO₃X     (I)
   
   

   in which R¹ is a C₁₀₋₂₀ alkyl radical and X is an alkali metal ion, an ammonium ion or an alkyl- or hydroxyalkyl-substituted ammonium ion,

   1 to 5 parts by weight of alkyl glycoside corresponding to formula II:
   
           R-O(G)_n     (II)
   
   

   in which R is a C₈₋₂₂ alkyl radical, G is a glycose unit and n is a number of 1 to 10,

   the ratio by weight of alkyl sulfate to alkyl glycoside being 25:1 to 8:1, and

   45 to 80 parts by weight of an inorganic carrier material of which at least 7% by weight consists of alkali metal silicate with a molar ratio of SiO₂ to alkali metal oxide of more than 2, are mixed with water in such a quantity that a mixture flowable and pumpable at temperatures below 80°C is formed and the water present in the mixture thus formed is removed by spray drying using drying gases having temperatures below 250°C to such an extent that a powder-form, free-flowing product is formed.
2. A process as claimed in claim 1, characterized in that 20 to 40 parts by weight of alkyl sulfate corresponding to formula I, 2 to 4 parts by weight of alkyl glycoside corresponding to formula II and 48 to 68 parts by weight of the inorganic carrier material are mixed with water in such a quantity that a mixture containing 40% by weight to 50% by weight of water is formed.
3. A process as claimed in claim 1 or 2, characterized in that the ratio by weight of alkyl sulfate to alkyl glycoside is 20:1 to 10:1.
4. A process as claimed in any of claims 1 to 3, characterized in that the drying gases have temperatures of 120°C to 240°C and, more particularly, 140°C to 210°C.
5. A process as claimed in any of claims 1 to 4, characterized in that 20 to 50% by weight of the inorganic carrier material consists of alkali metal silicate with a molar ratio of SiO₂ to alkali metal oxide of more than 2 and, more particularly, in the range from 2.5 to 3.5.
6. A process as claimed in any of claims 1 to 5, characterized in that, in addition to the alkali metal silicate, the inorganic carrier material contains an alkali metal carbonate, an alkali metal hydrogen carbonate, an alkali metal sulfate, a layer silicate or alumosilicate or a mixture thereof.
7. A process as claimed in any of claims 1 to 6, characterized in that the water is removed from the flowable aqueous mixture by spray drying to such an extent that the powder-form product formed contains no more than 15% by weight and, more particularly, 5% by weight to 15% by weight of water.